The present invention relates to a sheet feeder applicable to a laser printer, facsimile apparatus, electrophotographic copier or similar image recording apparatus and having an automatic sheet feeding function for feeding paper sheets one by one from a sheet feed tray or a sheet cassette by using a friction pad and a manual sheet feeding function for feeding paper sheets which are manually inserted one at a time.
In a prior art sheet feeder of the type described, manual feed is impracticable unless a release lever is operated every time a paper sheet is fed manually so as to cancel a force which constantly urges the bottom plate of a sheet feed tray. Hence, manual feed cannot be repeated without forcing an operator to withstand troublesome manipulations. In addition, even in a manual feed mode, a friction pad is held in pressing contact with a feed roller and therefore exerts a pressure on a paper sheet to be fed, rendering the sheet feeding force unstable.